Abstract

Sixty basal body temperature (BBT) charts were reviewed by three reproductive endocrinologists in an attempt retrospectively to predict the urinary luteinizing hormone (LH) surge. LH surges had been previously detected in all cycles with the use of a commercially available monoclonal antibody kit, Ovustick (Monoclonal Antibodies, Inc., Mountain View, CA). Surges were correctly predicted to the day (day 0) 18.3% to 30.0% of the time, to within 1 day on either side of day 0 56.7% to 70.0% of the time, to within 2 days 83.3% to 98.3% of the time, and to within 3 days 96.7% to 98.3% of the time. The BBT remains an inaccurate predictor of the day of the LH surge but does provide a reasonably accurate guide to the 2- to 3-day period on either side of the surge.

PIP:

The accuracy of basal body temperature (BBT) in retrospectively predicting the urinary luteinizing hormone (LH) surge was assessed in 60 cycles from 21 women undergoing artificial insemination with their husbands' semen. LH surges previously had been detected through use of commercially available monoclonal antibody kit, Ovustick. BBT charts were reviewed by 3 reproductive endocrinologists. Surges were correctly predicted to the day 18.3-30.0% of the time, to within 1 day on either side of day 0 56.7-70.0% of the time, to within 2 days 83.3-98.3% of the time, and to within 3 days 96.7-98.3% of the time. In addition, the physician who performed the inseminations calculated the relationship between the thermal nadir and the urinary LH surge. The nadir was noted on the day of the surge in 30% of cycles, between days -1 and +1 in 78.3%, and between days -2 and +2 in 100%. The results confirm the impression that the BBT is an inaccurate predictor of the precise day of the LH surge. On the other hand, it does provide a reasonably accurate guide to the 2-3 day period on either side of the LH surge. It is concluded that prospective use of the BBT, in which the endpoint for identifying the LH surge is the lowest temperature at midcycle before a sustained rise, can be useful in timing artificial insemination if multiple inseminations at 48-hour intervals are feasible.